This invention is related to commonly-assigned U.S. patent application, Ser. No. 371,784 filed June 20, 1973 entitled "Method for Aromatizing Soluble Coffee" wherein is disclosed a method for condensing the aromatic gases given off during the comminution of freshly roasted coffee in a vertically-mounted, scraped-wall heat exchanger which is cooled by means of liquid nitrogen. The condensed gases are collected at the bottom of the heat exchanger in the form of a frost or snow and this frost is mixed with a liquid glyceride and then combined with a coffee extract prior to drying the extract (e.g. freeze drying) or combined with a soluble coffee powder. This application is hereby incorporated by reference. This application is also related to commonly-assigned, concurrently-filed U.S. application, Ser. Nos. 471,633 now U.S. Pat. No. 3,939,291 and 471,632 which are also incorporated herein by reference.
Grinder gas, that is the gas which is released from roasted whole coffee beans when their internal cell structure is disrupted, such as during grinding of the beans and which also continues to be evolved from the disrupted and/or fractured bean for a short period thereafter, has long been recognized in the art as a highly desirable natural coffee aroma. The collection and stabilization of this aroma has however proven to be a difficult undertaking, especially when it is desired for use in a commercial-sized soluble coffee system.
The use of grinder gas as a means to enhance the jar aroma of a soluble coffee powder is disclosed in U.S. Pat. No. 3,021,218 to Clinton et al. which aromatizes the jar headspace and U.S. Pat. No. 2,306,061 to Johnston which condenses grinder gas aromatics onto chilled soluble coffee powder. The use of grinder gas condensates which are added to a liquid extract and dried in order to produce an improved cup aroma when the powder is dissolved in hot water is disclosed in U.S. Pat. No. 3,244,533 to Clinton et al. which homogenizes coffee oil in extract and then adds condensed grinder gas aromatics. Co-pending, commonly-assigned patent application, Ser. No. 252,883, filed May 12, 1972, now U.S. Pat. No. 3,821,447, discloses mixing condensed grinder gas frost with a liquid glyceride which mixture is then processed to remove excess water, such as by centrifugation, prior to being combined with soluble coffee solids (e.g. soluble powder).